Recently I’ve had a few comments on the blog addressing my recommendation for high quality cod liver oil during pregnancy. The commenters point to high amounts of Vitamin A as being toxic to an unborn fetus, which can cause birth defects.
However, I had a totally uneventful experience during my own pregnancy with Austin, in which I supplemented 1 tsp of cod liver oil every day for nine months, and the entire time that I breastfed. I made this choice after combing through as much science-based research as I could find in medical journals and studies, and also based on the recommendation of my midwife.
So what gives? Why the discrepancy? Why are so many women afraid of cod liver oil during pregnancy when the benefits are proven?
(For more information about having a healthy pregnancy, check out my ebook, Fit To Be Pregnant: 12 Steps to the Healthy, Comfortable, and Fit Pregnancy of Your Dreams.)
Vitamin A in Pregnancy
Vitamin A is an essential nutrient in fetal development, as it aids in cellular function and development. It can be found naturally in whole foods, including fruits and vegetables that convert Beta-carotene to vitamin A, or in retinol form, coming from animals. It can also be found in synthetic (man-made) form, sometimes under the names Acetate and Palmitate, normally added to vitamins and supplements.
A study performed in 1995 found that women who consumed more than 10,000 IU’s of Vitamin A per day — 4x the recommended amount — during early pregnancy were more likely to have babies born with birth defects (1 in 57, increasing as the amount of IU’s increased). They found that this risk includes animal form vitamin A (retinol) as well as supplements (the researchers did point out that foods and supplements rich in beta-carotene are not associated with an increased risk of birth defects).
Cod Liver Oil
Cod liver oil is a nutritional supplement derived from liver of cod fish. As with most fish oils, it has high levels of the omega-3 fatty acids, EPA and DHA (Wikipedia). Because vitamin A accumulates in the liver, cod liver oil has the potential to contain high amounts of the nutrient. Some companies also add a synthetic form of the vitamin to their supplements. Vitamin A is also added to most prenatal vitamins, which can then increase a pregnant mother’s consumption even more.
However, the benefits of cod liver oil during pregnancy are proven, see these studies:
- Use of cod liver oil during pregnancy associated with lower risk of Type I diabetes in the offspring
- Maternal Supplementation With Very-Long-Chain n-3 Fatty Acids During Pregnancy and Lactation Augments Children’s IQ at 4 Years of Age
- Relationship between dietary intake of cod liver oil in early pregnancy and birthweight
In addition to these benefits, fish and fish oil in general have been found to reduce risks of pre-term labor, pre-eclampsia, pregnancy and post-partum depression, and childhood allergies.
As I have stated on this site several times, I made a point not to make any decisions during my pregnancy based on fear (as I’ve also stated, I would never judge someone else who did, either). I made each decision very carefully with a combination of my midwife’s recommendations, science-based research from medical journals, and my own common sense. For example, I decided that having sushi every once in a while was ok for me, based on a common sense look at pregnancy around the world (Japanese women eat sushi during pregnancy). I kept exercising to the best of my ability during my pregnancy based on the studies of Dr. James Clapp, MD, even though rumors still pervade that it is dangerous. And I chose to take a safe dose of cod liver oil every day, despite warnings of Vitamin A toxicity, based on the above studies.
I took the Vitamin A warnings very seriously, and made sure that my chosen cod liver oil was whole food based and NOT synthetic, that it had the same ratio of Vitamin A to Vitamin D found in whole foods, and that the amount of Vitamin A did not come close to the unsafe level of 10,000 IU’s per day. In fact, a teaspoon of my cod liver oil contains only 850 IU’s, nowhere near the limit that was found to cause birth defects. My prenatal vitamin contained 5,000 IU’s of Vitamin A, but it was from beta-carotene, the safe form of Vitamin A.
Should I Supplement With Cod Liver Oil During Pregnancy?
I do think that it is always best to receive your vitamins and minerals from whole foods whenever it is possible, not just during pregnancy but for the rest of your life. Science has not yet been able to replicate the efficiency of our bodies at using the nutrients of whole foods. Supplements such as cod liver oil, fish oil, and prenatal vitamins should be a safety net, not a diet plan.
If you find that you are unable to get enough EPA and DHA through low-mercury, fatty fish or other whole food sources, and after you’ve spoken with your doctor and done your own research, you might choose to supplement with cod liver or fish oil:
- Read the label carefully.
- Make sure the vitamin A is from fish and not a synthetic version.
- Do not exceed 5,000-8,000 IU’s of retinol (animal-based vitamin A, such as cod liver oil, eggs, dairy, meat, etc.) or synthetic Vitamin A per day, or a combination of the two.
- Remember that vitamin A that comes from beta-carotene in fruits and vegetables is fine in any amount, as much of the vitamin is lost in the conversion of beta-carotene to retinol, resulting in much smaller amounts.
If you feel safer avoiding cod liver oil, that is absolutely your choice! Every mother should own her pregnancy and make educated decisions that she can live with. But I hope that this article cleared a few things up and made that decision a little bit easier.